 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.internal.preferences;

 import java.util.ArrayList ;
 import java.util.Collection ;
 import java.util.Collections ;
 import java.util.HashSet ;
 import java.util.Iterator ;

 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.jface.preference.PreferenceNode;
 import org.eclipse.jface.resource.ImageDescriptor;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.ui.IPluginContribution;
 import org.eclipse.ui.internal.registry.IWorkbenchRegistryConstants;
 import org.eclipse.ui.internal.registry.KeywordRegistry;
 import org.eclipse.ui.plugin.AbstractUIPlugin;

 /**
  * The WorkbenchPreferenceExtensionNode is the abstract class for all property
  * and page nodes in the workbench.
  *
  * @since 3.1
  */
 public abstract class WorkbenchPreferenceExtensionNode extends PreferenceNode implements IPluginContribution {
     
     private static final String TAG_KEYWORD_REFERENCE = "keywordReference"; //$NON-NLS-1$

     private Collection keywordReferences;
     
     private IConfigurationElement configurationElement;

     private ImageDescriptor imageDescriptor;

     private Image image;

     private Collection keywordLabelCache;
     

     /**
      * Create a new instance of the reciever.
      *
      * @param id
      * @param configurationElement
      */
     public WorkbenchPreferenceExtensionNode(String id, IConfigurationElement configurationElement) {
         super(id);
         this.configurationElement = configurationElement;
     }

     /**
      * Get the ids of the keywords the receiver is bound to.
      *
      * @return Collection of <code>String</code>. Never <code>null</code>.
      */
     public Collection getKeywordReferences() {
         if (keywordReferences == null) {
             IConfigurationElement[] references = getConfigurationElement()
                     .getChildren(TAG_KEYWORD_REFERENCE);
             HashSet list = new HashSet (references.length);
             for (int i = 0; i < references.length; i++) {
                 IConfigurationElement page = references[i];
                 String id = page.getAttribute(IWorkbenchRegistryConstants.ATT_ID);
                 if (id != null) {
                     list.add(id);
                 }
             }

             if (!list.isEmpty()) {
                 keywordReferences = list;
             } else {
                 keywordReferences = Collections.EMPTY_SET;
             }
             
         }
         return keywordReferences;
     }

     /**
      * Get the labels of all of the keywords of the receiver.
      *
      * @return Collection of <code>String</code>. Never <code>null</code>.
      */
     public Collection getKeywordLabels() {
         if (keywordLabelCache != null) {
             return keywordLabelCache;
         }
         
         Collection refs = getKeywordReferences();
         
         if(refs == Collections.EMPTY_SET) {
             keywordLabelCache = Collections.EMPTY_SET;
             return keywordLabelCache;
         }
         
         keywordLabelCache = new ArrayList (refs.size());
         Iterator referenceIterator = refs.iterator();
         while(referenceIterator.hasNext()){
             Object label = KeywordRegistry.getInstance().getKeywordLabel(
                     (String ) referenceIterator.next());
             if(label != null) {
                 keywordLabelCache.add(label);
             }
         }
         
         return keywordLabelCache;
     }
     
     /**
      * Clear the keyword cache, if any.
      */
     public void clearKeywords() {
         keywordLabelCache = null;
     }

     /* (non-Javadoc)
      * @see org.eclipse.jface.preference.IPreferenceNode#disposeResources()
      */
     public void disposeResources() {
         if (image != null) {
             image.dispose();
             image = null;
         }
         super.disposeResources();
     }

     /* (non-Javadoc)
      * @see org.eclipse.jface.preference.IPreferenceNode#getLabelImage()
      */
     public Image getLabelImage() {
         if (image == null) {
             ImageDescriptor desc = getImageDescriptor();
             if (desc != null) {
                 image = imageDescriptor.createImage();
             }
         }
         return image;
     }


     /* (non-Javadoc)
      * @see org.eclipse.jface.preference.IPreferenceNode#getLabelText()
      */
     public String getLabelText() {
         return getConfigurationElement().getAttribute(IWorkbenchRegistryConstants.ATT_NAME);
     }

     /**
      * Returns the image descriptor for this node.
      *
      * @return the image descriptor
      */
     public ImageDescriptor getImageDescriptor() {
         if (imageDescriptor != null) {
             return imageDescriptor;
         }
         
         String imageName = getConfigurationElement().getAttribute(IWorkbenchRegistryConstants.ATT_ICON);
         if (imageName != null) {
             String contributingPluginId = getConfigurationElement().getNamespace();
             imageDescriptor = AbstractUIPlugin.imageDescriptorFromPlugin(contributingPluginId, imageName);
         }
         return imageDescriptor;
     }
     
     /**
      * Return the configuration element.
      *
      * @return the configuration element
      */
     public IConfigurationElement getConfigurationElement() {
         return configurationElement;
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.ui.activities.support.IPluginContribution#getLocalId()
      */
     public String getLocalId() {
         return getId();
     }

     /* (non-Javadoc)
      * @see org.eclipse.ui.activities.support.IPluginContribution#getPluginId()
      */
     public String getPluginId() {
         return getConfigurationElement().getNamespace();
     }
 }

